JP4621270B2 - Optical filter - Google Patents

Description

  The present invention relates to an optical filter using localized plasmons.

  In recent years, Patent Document 1 and Non-Patent Document 1 have proposed hole-type optical filters in which openings are periodically arranged in a metal thin film and wavelength selection is performed using surface plasmons.

  Conventionally, although it depends on the film thickness, it has been considered that the transmittance of a metal thin film having an aperture diameter with a size equal to or smaller than the wavelength of light is less than 1%.

  However, as described in Patent Document 1, when an aperture having a predetermined size is arranged in a metal thin film at a period in accordance with the plasmon wavelength, the transmittance of light having a wavelength that induces surface plasmon is greatly improved. I understood that.

  Non-Patent Document 1 describes that an RGB transmission spectrum can be obtained using a hole-type optical filter using such surface plasmons. Specifically, it is disclosed that transmission spectra having wavelengths of 436 nm (blue), 538 nm (green), and 627 nm (red) were obtained using a metal thin film having sub-wavelength array openings.

Patent Document 2 discloses a wavelength filter using surface plasmons.
US Pat. No. 5,973,316 International Publication No. 2002/008810 Pamphlet Nature Vol. 424 14, August, 2003 (FIG. 4)

  In Patent Document 1 and Non-Patent Document 1, a filter having a transmission spectrum depending on the wavelength of surface plasmon induced on a metal surface is realized by periodically forming holes in a metal thin film having a relatively large area. is doing.

  However, such a hole-type metal thin film filter has a high light absorption because of a large proportion of metal. Therefore, in the metal thin film filter described in Patent Document 1, the transmittance is about 5 to 6% even if the transmittance is the highest peak.

  In such a filter with low transmittance, when it is desired to use the transmission spectrum, it is necessary to increase the intensity of the incident light in order to ensure the intensity of the transmission spectrum. For this reason, there is a possibility that the energy efficiency of the device using the Hall type filter will be low.

  In particular, the absorption of light by metals is not so much in the microwave region, but the absorption of light is large in the visible light region. If a hole-type metal thin film filter is used as a transmission filter in the visible light region, the range of application to actual devices Becomes narrower.

  Similarly, even if a hole-type filter is used as a reflection filter in the visible light region, the energy efficiency is low due to light absorption.

  Therefore, it is desired to provide an optical filter with less light absorption and higher transmittance or reflectance than a hole-type metal thin film filter in a wavelength band including the visible light region.

  By the way, in the filters described in Patent Document 1 and Patent Document 2, optical characteristics are controlled by periodically forming openings and protrusions having a pitch corresponding to the surface plasmon wavelength in a metal film having a relatively large area. is doing. That is, the surface plasmon waves having a wavelength corresponding to the pitch are selected by the interference between the surface plasmon waves propagating along the periodic structure, and are strengthened to increase the intensity of transmitted light and the intensity of reflected light. .

  Therefore, in the filters described in Patent Document 1 and Patent Document 2, the pitch of the periodic structure is a dominant factor in the optical characteristics of the filter. And if a wavelength is determined in order to express a desired optical characteristic, the pitch of a periodic structure will be determined according to this. That is, when a desired wavelength is selected, the density of the openings and protrusions is restricted, and it is difficult to increase the transmittance and the reflectance.

  In addition, since the filter described in the above-mentioned document requires periodic openings and arrangement of protrusions, the size and area of the filter must be several times the pitch. That is, the filters of Patent Document 1 and Patent Document 2 do not necessarily have a high degree of freedom regarding size selection.

  Therefore, it is desired to provide an optical filter having a high degree of freedom in size selection as compared with a filter using surface plasmons based on a periodic structure of a metal film having a relatively large surface area.

  An optical filter according to the present invention is an optical filter that transmits or reflects light having a first wavelength, and includes a dielectric substrate and a plurality of first metal structures on the surface of the dielectric substrate. A first metal structure group that is two-dimensionally provided in a state isolated in a direction, and a dielectric layer that covers the first metal structure group. Having a first length in one direction and a second length in a second direction orthogonal to the first direction, the first length and the second length being: The first metal structure has a length equal to or shorter than the first wavelength, and the light incident on the dielectric substrate or the dielectric layer resonates with the surface of the first metal structure. According to the induced localized plasmon, the transmittance of the first wavelength is minimized or the reflectance is maximized.

  According to the present invention, it is possible to provide an optical filter with less light absorption and higher transmittance or reflectance than a hole-type metal thin film filter in a wavelength band including a visible light region.

  In addition, according to the present invention, it is possible to provide an optical filter having a higher degree of freedom in size selection than a filter using surface plasmons based on a periodic structure of a metal film having a relatively large surface area.

  The inventors focused on the fact that a hole-type metal thin film has large light absorption and low transmittance and reflectance, and examined a dot-type optical filter in which metal structures are periodically arranged on a dielectric substrate. did.

  Metal fine particles, particularly particles having a size of the order of or less than the wavelength of light, can generate localized plasmon resonance (LSPR: Localized Surface Plasmon Resonance).

  Here, plasmon is a collective oscillation of free electrons on a metal surface excited by an external electric field such as light. Since electrons are charged, polarization due to the density distribution of free electrons occurs when the electrons vibrate. The phenomenon in which the polarization and the electromagnetic field are combined is called plasmon resonance.

  In particular, the resonance phenomenon between plasma vibration of free electrons generated on the surface of metal fine particles and metal microstructure and light is called localized plasmon resonance (LSPR).

  In other words, collective vibrations of free electrons on the surface of metal fine particles are excited by an external electric field such as light, and the vibration generates an electron density distribution and accompanying polarization, generating an electromagnetic field that is localized in the vicinity of the particle. To do.

  When comparing filters of the same area, a dot-type optical filter in which a plurality of metal structures (for example, periodically) are arranged on a dielectric substrate has a metal portion compared to a hole-type optical filter. Can be reduced. Therefore, since it is a structure which can take a substantial opening part easily and can suppress absorption of the light by a metal, the whole transmittance | permeability can be made higher than a hall | hole type | mold.

  FIG. 14 is a schematic diagram of a dot-type optical filter in which a plurality of metals 1402 are arranged on a dielectric substrate 1401 (for example, at a certain period). By comprising in this way, the transmission spectrum which has the minimum value of the transmittance | permeability at a specific wavelength can be obtained. This is because light of a specific wavelength is absorbed and scattered by localized plasmon resonance. As long as the LSPR is a metal structure having a thickness of several nanometers or more, even a minute one can be expressed.

  However, as a result of investigations by the present inventors, it has been found that simply disposing a metal 1402 on a dielectric substrate 1401 causes an undesirable phenomenon as an optical filter.

  That is, if the metal 1402 is simply disposed on the dielectric substrate 1401, the frequency of plasmon resonance at the interface between the air and the metal (metal upper surface 1403) and the interface between the metal 1402 and the dielectric substrate 1401 (metal lower surface 1404). ) Plasmon resonance frequency is different. As a result, it has been found that the optical spectrum width is expanded, peak splitting, etc. occur, and undesirable characteristics as an optical filter are developed.

  When this optical filter is used as a reflection filter, the reflection characteristics differ depending on whether incident light is incident from the dielectric substrate side or from the metal side. For this reason, in order to express desired optical characteristics, the optical filter allows only incident light from one direction, and there is a possibility that the degree of freedom in designing an optical system using such an optical filter may be reduced.

  Further, when dust or the like adheres to the metal surface, there is a problem that a peak wavelength shift or the like occurs.

  Therefore, when a structure in which a metal is embedded in a dielectric was examined, it was possible to suppress the splitting of the spectral peak and the expansion of the peak width caused by the difference in the plasmon resonance frequency at the interface between air and metal.

  In addition, it has become possible to prevent metal oxidation and further suppress changes in optical properties (such as a shift in peak wavelength) due to dust and the like adhering to the metal surface.

  By the way, if it is going to use the dielectric multilayer filter, the dye filter, etc. which are general optical filters for a device, the film thickness more than the wavelength of light is needed, Specifically, the film thickness is about 1 micrometer or more. Become.

  On the other hand, in the optical filter according to the present invention, it is possible to constitute a filter having a metal thickness of about 100 nm or less. Even if the protective layer is stacked on the metal structure with a thickness of about 100 nm, the film thickness of all layers can be suppressed to about 200 nm. Therefore, it is possible to provide a filter having a thinner film thickness than conventional filters.

  Accordingly, if the optical filter according to the present invention is used for a light receiving element such as a CCD sensor or a CMOS sensor, the light receiving element can be reduced in size. In addition, when the optical filter according to the present invention is used for a light receiving element, it is possible to alleviate a shortage of received light amount due to a decrease in the expected angle of each pixel as the number of pixels of the light receiving element increases.

(First embodiment: single-layer optical filter and laminated optical filter)
Hereinafter, embodiments according to the present invention will be described with reference to the drawings.

  FIG. 1B is a top view of the optical filter according to the first embodiment of the present invention, and FIG. 1A is a cross-sectional view taken along line AA ′.

  A dielectric layer 130 is provided on the surface of the dielectric substrate 110, and a plurality of metal structures 120 are provided between the dielectric substrate 110 and the dielectric layer 130.

  The metal structure 120 is provided two-dimensionally and periodically in a state of being isolated in the in-plane direction of the dielectric substrate 110, and is configured as a metal structure group. For the sake of explanation, reference numerals 121 and 122 are assigned to the two first metal structures constituting the first metal structure group.

  The optical filter according to the present invention is based on localized plasmon resonance expressed by a single metal structure, but it is preferable to periodically provide the metal structure 120 from the following points.

  That is, when plasmon resonance occurs, an electric field oozes out from each metal structure, so if the metal structures are arranged within the range where the electric field oozes, the resonance conditions of each metal structure are affected by each other. become. In order to reduce this influence, it is preferable that the metal structure and the metal structure adjacent to the metal structure are disposed at positions that are electromagnetically equivalent, that is, periodically.

  If each metal structure is periodically arranged in this way, a shift in resonance conditions in each metal structure is suppressed, and local plasmon resonance having the same phase can be induced in each structure at the same resonance wavelength. As a result, a transmission spectrum having a deep resonance peak dip and a narrow peak width can be obtained. In addition, since the generation of diffracted light can be suppressed, the influence on the transmission spectrum shape can also be reduced.

  By the way, if the metal structures are too close to each other, the resonance conditions of the metal structures are strongly influenced by each other. As a result, a desired resonance wavelength and spectrum width cannot be obtained, and the transmittance may be lowered. Therefore, considering that the electric field of a metal structure leaks to a distance of about the size of the structure itself at the time of localized plasmon resonance, the distance between the metal structures is separated by about the size of the structure. Preferably it is.

  More preferably, the distance between the metal structures is such that the aforementioned exudation of the electric field does not overlap, that is, the distance between the metal structures is about twice or more the size of the metal structure itself. It is preferred that they are separated.

  On the other hand, when the distance between the metal structures is about three times the size of the structure itself, the dip of the transmission spectrum becomes shallow.

  Accordingly, the interval between the metal structures provided periodically is preferably 1 or more times the size of the structure itself, more preferably 1 to 3 times, and more preferably about 2 times. It is.

  In FIG. 1, the first metal structure 121 has a first length 141 in a first direction 140 and a second length in a second direction 150 orthogonal to the first direction 140. 151. Here, the first length 141 and the second length 151 are set to a length equal to or shorter than the wavelength of light in the visible light region, for example. Even if the wavelength of the plasmon induced in the metal structure is the lowest order mode (dipole mode), the half wavelength of the plasmon is substantially the same as the size of the metal structure. For this reason, for example, the size of the structure that can excite plasmons with visible light is shorter than the excitation wavelength of visible light. Therefore, these lengths are set to be equal to or less than the wavelength of light in the visible light region.

  It is also a preferred embodiment that the first length 141 and the second length 151 are set to be equal to or less than the plasmon resonance wavelength (below the first wavelength).

  Here, as an example, the first metal structure 121 has a square shape in which the first length and the second length are the same, and one side is 120 nm. Although a square shape is preferable from the viewpoint of designability of optical characteristics, a circular, elliptical, or other polygonal metal can be used as the metal structure. For example, a circular shape is preferable because polarization dependency can be suppressed and manufacturing accuracy can be easily maintained.

  In the case of using a metal structure that is not square, the first length is handled as a reference numeral 1801 and the second length is a reference numeral 1802 as shown in FIG.

  The shape of the metal structure is not limited to this, and various shapes can be taken. However, the first length or the second length can be regarded as the maximum width of the metal structure.

  In the present embodiment, the metal structure and the light incident on the dielectric substrate or the dielectric layer resonate, so that localized plasmons induced on the surface of the metal structure cause a predetermined wavelength in the visible light region ( The transmittance of the first wavelength is a minimum value.

  In the first metal structure group illustrated in FIG. 1, the period 145 and the period 155 in which the metal structure 120 is provided are less than or equal to the wavelength of light in the visible light region, more preferably less than or equal to the plasmon resonance wavelength (first It is also a preferred form to be less than the wavelength). This is because when the period of the metal structure is longer than the wavelength range of the light of interest, high-order diffracted light is generated, and the intensity of the 0th-order diffracted light may be reduced.

  In addition, it is also preferable that the period 145 and the period 155 in which the metal structure 120 is provided be smaller than the plasmon resonance wavelength (first wavelength) of the first metal structure group. When the period of the metal structure is close to the plasmon resonance wavelength, light having a wavelength causing Woods anomaly is combined with the plasmon resonance, the peak shape by the plasmon resonance is sharpened, and the depth of the transmittance minimum value at the resonance wavelength is increased. It will be shallow. Here, the Woods anomaly refers to a phenomenon in which incident light is diffracted by a periodic structure, and the diffracted light propagates in the vicinity of the surface of the metal periodic structure in parallel with the surface.

  Here, as an example, the periods 145 and 155 are set to 400 nm for the purpose of causing plasmon resonance in the red wavelength band.

  In addition, it is also preferable that the interval 152 between the first metal structures 121 and 122 is larger than the first length 141 and the second length 151. By setting such an interval, it is possible to suppress an increase in spectral peak width, a shift in peak wavelength, and the like due to strong near-field interaction between metal body structures.

  In addition, it is also a preferable form that the thickness 160 of the metal structure 120 is set to be equal to or less than the wavelength of light in the visible light region, preferably equal to or less than the plasmon resonance wavelength (first wavelength or less). This is because if the thickness of the metal structure is set too large in the microfabrication process when manufacturing the filter, the manufacturing error increases. Here, as an example, the thickness 160 is 30 nm.

  As a material of the metal structure 120, aluminum, gold, silver, platinum, or the like can be used. Among these, aluminum has a higher plasma frequency than silver, and it is easy to design a filter with optical properties that cover the entire visible region (Ag: ˜3.8 eV (˜325 nm)), Al: ˜15 eV. (˜83 nm)).

  In addition, since aluminum is less oxidized and chemically stable than silver or the like, it can stably exhibit predetermined optical characteristics for a long period of time.

  Furthermore, since aluminum has a larger imaginary part of dielectric constant than silver, sufficient light shielding properties can be exhibited even if the film thickness is made thinner than silver, and fine processing is easy.

  In addition, since aluminum is extremely chemically inert like platinum, there is no difficulty in that fine processing by dry etching is difficult.

  The metal structure 120 may be a mixture or alloy containing aluminum, gold, silver, and platinum.

  As a material of the dielectric substrate 110, for example, a material that transmits light in the visible light region, such as quartz (silicon dioxide), a metal oxide such as titanium dioxide, or a material having a high transmittance such as silicon nitride is appropriately selected. Can do. A polymer material such as polycarbonate or polyethylene terephthalate can also be used as the material of the dielectric substrate 110.

  The material of the dielectric layer 130 can be appropriately selected from quartz (silicon dioxide), titanium dioxide, silicon nitride, and the like, similarly to the dielectric substrate 110. A polymer material such as polycarbonate or polyethylene terephthalate can also be used as the material of the dielectric layer 130.

  Here, the difference in dielectric constant between the dielectric substrate 110 and the dielectric layer 130 is preferably 5% or less. When the dielectric constant of the dielectric substrate 110 and the dielectric constant of the dielectric layer 130 are greatly different, the excitation wavelength of plasmon generated at the interface between the metal structure 120 and the dielectric substrate 110 and the interface between the metal structure 120 and the dielectric layer 130 This is because the excitation wavelength of the plasmon generated in is greatly different. As a result, there is a possibility that an undesired resonance wavelength peak or peak width may be increased.

  Therefore, it is most preferable that the dielectric constant of the dielectric substrate and the dielectric constant of the dielectric layer are the same.

  Further, it is preferable that the thickness 170 obtained by subtracting the thickness 160 of the metal structure 120 from the thickness of the dielectric layer is not too thick. This is because if the dielectric layer is too thick, the dielectric layer 130 constitutes a kind of Fabry-Perot resonator, and there is a concern that many fine dips may appear in the transmission spectrum.

  Therefore, for example, it is preferable that the resonator mode of the Fabry-Perot resonator does not exist in the wavelength range of the full width at half maximum of the plasmon resonance of the metal structure 120.

  For this purpose, at least the resonator mode interval (FSR) needs to be wider than the full width at half maximum of plasmon resonance, and the condition is expressed as follows.

Where λ _res is the plasmon resonance wavelength of the metal structure, n is the refractive index of the dielectric layer, and Δλ _FW is the full width at half maximum of the resonance spectrum of the metal structure.

  Here, d in the formula corresponds to the thickness of the dielectric layer. Therefore, for example, typically, the full width at half maximum of plasmon resonance is 100 nm. Therefore, when the wavelength of plasmon resonance is 650 nm and the refractive index of the dielectric layer is 1.46, d is calculated to be 1447 nm. For this reason, when the wavelength region of interest is 650 nm ± 50 nm, the thickness of the dielectric layer needs to be less than or equal to d in order to secure an FSR of 100 nm or more in this wavelength region.

  It is also a preferable form that the resonator mode of the Fabry-Perot resonator appears only in a wavelength region shorter than the wavelength region of interest.

  The resonator mode of the Fabry-Perot resonator appears at a wavelength equal to twice the resonator length. When the wavelength region of interest is a wavelength region within the resonance width of the metal structure, the shortest wavelength of the wavelength region of interest is a value obtained by subtracting the half width of resonance from the resonance wavelength. Therefore, since the resonator mode of the Fabry-Perot resonator becomes shorter than this wavelength, the thickness of the dielectric layer needs to be equal to or less than the value d represented by the following formula.

Where λ _res is the plasmon resonance wavelength of the metal structure, n is the refractive index of the dielectric layer, and Δλ _HW is the half width at half maximum of the resonance spectrum of the metal structure.

  For example, when the resonance wavelength is 450 nm and the half width of resonance is 50 nm, d is calculated as 137 nm when the refractive index is 1.46. Therefore, in order to prevent the Fabry-Perot resonator mode from appearing on the shorter wavelength side than 400 nm, which is the shortest wavelength in the visible light region, it is preferable that the thickness of the dielectric layer be less than or equal to this d.

  On the other hand, it is not so preferable that the thickness of the dielectric layer is too thin, and it is preferable to have a certain thickness. That is, it is preferable that the thickness 170 obtained by subtracting the thickness of the metal structure 120 from the thickness of the dielectric layer is equal to or more than the first length 141 and the second length 151 included in the metal structure 120. Further, at least the thickness 170 is preferably about 100 nm.

  This is because the expansion of the near field generated by the metal structure 120 is typically about the size of the metal structure 120 itself or about 100 nm. If the dielectric layer occupies a space within the distance of the near-field region where the metal structure 120 is generated from the surface of the metal structure 120, foreign matter or the like is mixed in the near-field region where the metal structure 120 is generated. And it can suppress that the optical characteristic of the metal structure 120 changes.

(Calculation result)
FIG. 2 shows the result of numerical calculation using the above structure. That is, the optical filter uses aluminum as the metal structure and has a first length and a second length of 120 nm, a period of 400 nm, and a thickness of 30 nm. The transmission spectrum of this optical filter is the transmission spectrum 201, and it can be seen that the optical filter functions as an optical filter that strongly absorbs light in the vicinity of a wavelength of 650 nm.

  Since the wavelength of 650 nm is a red band, the acronym Red is used as the optical filter R. Since this optical filter reflects and absorbs red wavelengths, blue-green, which is a complementary color of red, is observed as a transmission spectrum.

  Furthermore, the wavelength, spectrum width, and intensity of the transmission spectrum can be changed by changing the diameter and period of the metal structure.

  For example, by setting the length to 100 nm, the period to 310 nm, and the thickness to 30 nm, an optical filter having a transmission spectrum 202 having absorption in the vicinity of green (wavelength 550 nm) in the visible range can be configured. This is an optical filter G. When the transmission spectrum of the optical filter G is observed, a reddish purple color that is a complementary color of green can be observed.

  Similarly, by setting the length to 70 nm, the period to 250 nm, and the thickness to 30 nm, an optical filter having a transmission spectrum 203 having absorption in the vicinity of blue (wavelength 450 nm) in the visible region can be configured. This is designated as an optical filter B. When the transmission spectrum of the filter B is observed, yellow that is a complementary color of blue can be observed.

  Note that the reflection spectrum of the optical filter according to the present embodiment has a maximum reflectance in the vicinity of the wavelength at which the transmittance is a minimum value. Therefore, the optical filter according to the present embodiment can be used not only as a transmission filter but also as a reflection filter that increases the reflectance at a desired wavelength.

(Design guidelines)
Hereinafter, the relationship between the parameters constituting the metal structure group and optical characteristics will be described.

  Localized plasmon resonance induced in a metal structure is a charge density distribution associated with plasma oscillation of free electrons in the metal structure. The charge density distribution and the optical characteristics of the metal structure are affected by the shape of the structure. The

  For example, while maintaining the length of the metal structure in the direction orthogonal to the polarization direction of the light irradiated to the metal structure, the thickness of the metal structure, and the period of arranging the metal structure, the metal in the polarization direction When the length of the structure is increased, the resonance wavelength shifts to the longer wavelength side.

  For this reason, it can be seen that in order to generate the wavelength of localized plasmon resonance of the metal structure on the longer wavelength side, the length of the polarization direction of the metal structure may be increased. This tendency is shown in FIG. According to the table shown in FIG. 17B, as the length of the polarization direction of the metal fine particles increases, not only the resonance wavelength shifts to a longer wavelength, but also the peak width widens and the transmittance at the absorption peak decreases. I understand that. Note that the polarization of light incident on the optical filter does not necessarily have to be strictly along the longitudinal direction or the lateral direction of the metal fine particles.

  Further, as shown in FIG. 19A, the resonance wavelength shifts to the short wavelength side as the length of the metal structure in the direction orthogonal to the polarization becomes longer. Further, FIG. 19B shows that the resonance width increases and the transmittance at the resonance wavelength tends to decrease as the length of the metal structure perpendicular to the polarization increases.

  As shown in FIGS. 20A and 20B, when the thickness of the metal structure is increased, the resonance wavelength is shortened, the transmittance at the resonance wavelength is decreased, and the resonance width is slightly decreased. It turns out that there is a tendency.

  Using this, the spectral shape can be improved from the transmission spectrum 2201 to the transmission spectrum 2202 as shown in FIG.

  In the transmission spectrum 2201, a sharp dip due to Woods anomaly exists in the spectrum near a wavelength of 530 nm. A transmission spectrum 2201 is an optical spectrum in the case where metal dots made of aluminum having a side of 150 nm and a thickness of 90 nm are arranged in a regular triangular lattice pattern with a period of 400 nm. On the other hand, the transmission spectrum 2202 is obtained when the film thickness is increased to 150 nm.

  That is, by increasing the film thickness, the resonance wavelength of the dot array is shifted to the short wavelength side, and overlapping with the sharp dip of the Woods anomaly makes the spectrum shape unimodal and narrows the resonance width. You can also.

  In this way, by setting the metal film thickness to a predetermined value, it is possible to hide an undesirable dip from the spectrum.

  Further, as shown in FIGS. 21A and 21B, when the period in which the metal structure is provided increases, the resonance wavelength becomes longer, the transmittance at the resonance wavelength increases, and the resonance width becomes It can be seen that it tends to decrease.

  Based on such knowledge, it is possible to optimize the parameters of the metal structure and the metal structure group, and it is possible to design an optical filter having a resonance wavelength at a desired wavelength.

  According to the study by the present inventors, in order to set the resonance wavelength of the optical filter to a red band (550 nm or more to less than 650 nm), the first length and the second length of the metal structure are set to 110 nm or more and 160 nm. It is necessary to set the following range. Further, it is necessary to set the thickness of the metal structure in the range of 10 nm to 200 nm and the period in the range of 340 nm to 450 nm.

  Further, in order to set the resonance wavelength of the optical filter to a green band (from 450 nm to less than 550 nm), it is necessary to set the first length and the second length of the metal structure within a range of 90 nm to less than 130 nm. is there. In addition, the thickness of the metal structure must be in the range of 10 nm to 200 nm, and the period in which the metal structure is provided must be set in the range of 260 nm to 340 nm, preferably 270 nm to 330 nm.

  Further, in order to set the resonance wavelength of the optical filter to a blue band (from 350 nm to less than 450 nm), it is necessary to set the first length and the second length of the metal structure in the range of 60 nm to less than 100 nm. is there. In addition, the thickness of the metal structure must be in the range of 10 nm to 200 nm, and the period in which the metal structure is provided must be set in the range of 180 nm to 280 nm, preferably 200 nm to 270 nm.

  The optical filter of the present embodiment has been described as having an absorption or reflection peak wavelength in the visible light region. On the other hand, an optical filter in the near ultraviolet region can be obtained by reducing the size and the period of the metal structure compared to the design value in the visible light region. Similarly, an optical filter in the near infrared region can be obtained by increasing the size of the metal structure and increasing the period.

(Second embodiment: Bayer array)
In the present embodiment, an RGB filter having a Bayer array will be described.

  In FIG. 3, for example, the optical filter R (transmission spectrum 201) described above is disposed in a region 301, the optical filter G (transmission spectrum 202) is disposed in a region 302, and the optical filter B (transmission spectrum 203) is disposed in a region 303. To do. With such an arrangement, it is possible to configure a Bayer array color filter using the filter according to the present invention.

  This color filter can be used as a color filter for an image sensor. In this case, the region 301 or the like has an area corresponding to one pixel, but the region 301 or the like may have a larger area than the region occupied by the photoelectric conversion element (photoelectric conversion unit).

  In the present embodiment, the size of the metal structure is different for each region and the period in which the metal structure is provided is different, but the present invention is not limited to this configuration. For example, metal structure groups that differ only in the period of the metal structure may be arranged in each region. Moreover, the metal structure group from which only the magnitude | size of a metal structure differs may be arrange | positioned in each area | region.

  That is, two or more first metal structure groups are provided, and the periods in which the first metal structures are provided are different from each other, and the first metal structure group is a phase on the surface of the dielectric substrate. They may be arranged in different areas.

  Moreover, the 2nd metal structure group which consists of a 2nd metal structure which is a shape different from the 1st metal structure which comprises a 1st metal structure group may be arrange | positioned in each area | region. That is, the second metal structure has a third length in the first direction, has a fourth length in the second direction, and the third length is the first metal structure. Is different from the first length of the first metal structure or the fourth length is different from the second length of the first metal structure. The third length and the fourth length are preferably equal to or shorter than the second wavelength.

  As a result, the second metal structure group can reduce the light transmittance at a wavelength (second wavelength) different from the resonance wavelength (first wavelength) of the first structure group.

  In the present specification, the first metal structure group and the second metal structure group mean that the shapes of the metal structures constituting the structure group are different. That is, even if the periods of the metal structures are different, the term “first metal structure group” is used if the shapes are the same. Further, if the shapes of the metal structures are different, the term “second metal structure group” is used regardless of whether the periods are the same or different.

(Third embodiment: triangular lattice)
FIG. 16 is a view showing an embodiment in which metal structures are arranged in a triangular lattice shape. In the case of the triangular lattice arrangement, the unit vector components of the lattice are not orthogonal, so that the dependence of the optical characteristics of the filter on the incident light polarization can be reduced as compared with the square lattice arrangement.

  Such a triangular lattice arrangement can also be expressed as a plurality of metal structure groups arranged in a square lattice are arranged in an overlapping region.

  That is, the first metal structure group 1602 configured by the first metal structure 1601 and the second metal structure group 1604 configured by the second metal structure 1603 are arranged in overlapping regions. It is possible to express that

(Fourth embodiment: overlap of two or more structures)
In the present embodiment as well, as in the third embodiment, an example in which a plurality of metal structure groups are arranged in an overlapping manner will be described.

  FIG. 4A shows an example in which the first metal structure groups having different periods are arranged in an overlapping manner. The first metal structure 401 constituting the first metal structure group 402 is provided at a period 405, and the first metal structure 403 constituting the first metal structure group 404 is provided at a period 406. It has been. As described above, in this embodiment, since the arrangement periods of the metal structures are different from each other, it is possible to simultaneously develop the optical characteristics of the two metal structure groups.

  That is, the optical filter of FIG. 4A has two or more of the first metal structure groups in the in-plane direction of the dielectric substrate, and the two or more first metal structure groups are included. The periods in which the first structural body is provided are different from each other. In addition, the two or more first metal structure groups are arranged in overlapping regions.

  FIG. 4B shows an example in which the first metal structure and the second metal structure are arranged in an overlapping region. The first metal structure 407 constitutes a first metal structure group, and the second metal structure 408 constitutes a second metal structure group. Thus, since the shape of the metal structure which comprises a metal structure group differs, it becomes possible to express each optical characteristic which two metal structure groups have simultaneously.

  That is, the optical filter of FIG. 4B is two-dimensionally in a state where a plurality of second metal structures are isolated in the in-plane direction of the dielectric substrate, separately from the first metal structure group. It has the 2nd metal structure group provided periodically. The second metal structure has a third length in the first direction and a fourth length in the second direction, and the third length and the fourth length are It is below the 2nd wavelength different from the 1st wavelength. The third length is different from the first length, or the fourth length is different from the second length. The first metal structure group and the second metal structure group are: Arranged in overlapping areas. As a result, the resonance wavelength (first wavelength) of the first metal structure is different from the resonance wavelength (second wavelength) of the second metal structure.

(Fifth embodiment: single-row filter)
In the present embodiment, a single column filter will be described.

  In FIG. 5, the first metal structure 509 has a first length 504 in a first direction 502 and a second length in a second direction 503 in a direction orthogonal to the first direction 502. 505. The first metal structures 509 are periodically arranged in the first direction 502, thereby constituting a first metal structure group 501.

  The second metal structure 510 has a third length 507 in the first direction 502 and a fourth length 508 in the second direction 503. The second metal structures 510 are periodically arranged in the first direction 502, thereby constituting a second metal structure group 506.

  These metal structure groups 501 and 506 generate plasmon resonance for light of different wavelengths, respectively, and as a result, the transmittance of light of different wavelengths can be reduced. Therefore, the optical filter having the structure shown in FIG. 5 can be used for spectroscopy or the like because the wavelength at which the transmittance is reduced varies depending on the light irradiation position.

  Note that the period that the metal structure 509 shown in FIG. 5 has in the first direction is different from the period that the metal structure 510 has in the first direction, but the period is the same as shown in FIG. May be.

  That is, the optical filter according to the present embodiment includes a first metal structure group and a second metal structure group configured by providing a plurality of metal structures in an isolated state in the in-plane direction of the dielectric substrate. And have. The first metal structure group and the second metal structure group are disposed in different regions on the surface of the dielectric substrate, and the first metal structure body is periodically disposed in the first direction. ing. Further, the first length and the second length of the first metal structure are equal to or shorter than the first wavelength. In addition, the second metal structures constituting the second metal structure group are periodically arranged in the first direction. The second metal structure has a third length in the first direction and a fourth length in the second direction, and the third length and the fourth length. Is a length equal to or shorter than a second wavelength different from the first wavelength. Then, as a result of the difference between the first length and the third length, or the difference between the second length and the fourth length, the resonance wavelength (first wavelength) of the first metal structure. And the resonance wavelength (second wavelength) of the second metal structure is different.

(Sixth embodiment: multilayer optical filter)
In the present embodiment, the stacked optical filters will be described.

In FIG. 7, a first metal structure group 702 is formed on a dielectric substrate 701 and is further covered with a first dielectric layer 703. A second metal structure group 704 is disposed on the first dielectric layer 703, and a second dielectric layer (another dielectric layer) 705 is formed thereon.

  Thereby, an optical filter having a transmission spectrum expressed by the product of the transmission spectrum 201 and the transmission spectrum 203 shown in FIG. For example, by laminating the optical filter R and the optical filter B, an optical filter having a transmission spectrum of the product of the transmittance of the optical filter R and the optical filter B can be obtained. This filter has a maximum transmittance near the wavelength of 550 nm. Thus, by stacking filters that function as complementary color filters in a single layer, it is also possible to function as primary color filters.

The configurations of the first metal structure group 702 and the second metal structure group 704 have different in-plane arrangement periods or different metal structure shapes.

Since the first metal structure group 702 and the second metal structure group 704 have different configurations, these layers generate plasmon resonance with respect to different wavelengths. As a result, the transmittance of the optical filter according to the present embodiment is minimized with respect to at least two wavelengths.

  This means that it has a function as a band-pass filter that passes a wavelength between the two minimum wavelengths.

Therefore, the first metal structure group 702 and the second metal structure group 704 which are single layers have a function of a complementary color filter, but a primary color having both characteristics by stacking these layers. A filter function can be expressed.

That is, the multilayer optical filter according to the present embodiment is a multilayer optical filter in which another dielectric layer is further formed on the surface of the dielectric layer. A plurality of second metal structures are provided two-dimensionally and periodically between the dielectric layer surface and another dielectric layer in a state of being isolated in the in-plane direction of the dielectric layer surface. A second metal structure group is included. A second metal structure forming the second metal structure group is in a first direction having a third length of, and a fourth length of the second direction, the third The length and the fourth length are not more than the second wavelength, which is different from the first wavelength. The first length is different from the third length or the second length is different from the fourth length, or the period in which the second metal structure is provided and the first metal structure is The provided period is different. As a result, the second metal structure group can reduce the transmittance at a resonance wavelength ( second wavelength) different from the resonance wavelength (first wavelength) of the first structure group.

  In the laminated optical filter according to the present embodiment, it is also a preferred form that the laminated optical filters are laminated at a lamination interval in which almost no near-field interaction occurs. Specifically, the stacking interval is preferably 100 nm or more.

  In Example 1, an RGB absorption / reflection filter manufacturing method and optical characteristics will be described.

  In FIG. 8A, 30 nm thick aluminum is deposited as a metal thin film layer 802 on the surface of a dielectric substrate 801 made of a quartz substrate having a thickness of 525 μm, and an electron beam drawing (EB) resist 803 is applied thereon. It is formed by. Note that the method for forming the metal thin film layer 802 is not limited to vapor deposition, and may be sputtering or the like.

  Next, the resist 803 is patterned using an EB drawing apparatus. The resist pattern has a square shape with a side of about 120 nm and is arranged in a square lattice pattern with a period of about 400 nm. With this resist pattern as an etching mask, the metal thin film structure 804 can be formed by dry etching with plasma of a mixed gas of chlorine and oxygen. The dry etching gas is not limited to chlorine and oxygen, and may be argon or other gas.

  Further, the etching mask manufacturing method is not limited to EB drawing, and photolithography or the like may be used. Further, the metal thin film layer 802 may be patterned by a lift-off process after a resist pattern is formed on the dielectric substrate 801 by EB drawing, photolithography, or the like, and the metal thin film layer 802 is formed. In addition, the metal thin film layer 802 may be directly processed using a focused ion beam processing apparatus (FIB processing apparatus).

  Next, a quartz thin film having a thickness of 300 nm is formed as a dielectric layer 805 on the metal thin film structure 804 by sputtering. The optical filter thus formed is shown in FIG. Note that the film formation method is not limited to sputtering, and film formation by CVD or SOG may be applied.

  FIG. 9A shows a transmission spectrum of the optical filter thus manufactured. By numerical calculation, the transmission spectrum R is obtained as indicated by reference numeral 901, and it can be seen that this filter has a minimum transmittance (absorption peak) near the wavelength of 650 nm. Since the wavelength showing the absorption peak corresponds to red in the visible range, it can be seen that this filter functions as a complementary color filter that absorbs red.

  Further, by arranging the metal thin film structure 804 with a diameter of about 100 nm, a thickness of about 30 nm, and a period of about 310 nm, a transmission spectrum G indicated by reference numeral 902 is obtained. Similarly, a transmission spectrum B indicated by reference numeral 903 is obtained by setting the diameter to about 70 nm, the thickness to 30 nm, and the period to about 250 nm. Each of these is an optical filter that absorbs RGB, and functions as a complementary color filter.

  Further, the reflection spectrum of the filter of the present embodiment has the maximum reflectance at substantially the same wavelength as the wavelength at which the transmittance is minimized.

  Therefore, as shown in FIG. 9B, by using the optical filter of this embodiment as a reflection filter, a reflection spectrum R indicated by reference numeral 904 can be obtained from a filter having a transmission spectrum R. Similarly, a filter having a transmission spectrum G can obtain a reflection spectrum G indicated by reference numeral 905, and a filter having a transmission spectrum B can obtain a reflection spectrum B indicated by reference numeral 906. As described above, these optical filters can function as optical filters that increase the reflectance of red, green, and blue in the visible range.

  In the present embodiment, the example in which the metal structures are arranged in a square lattice shape has been described. However, a triangular lattice arrangement may be used.

  Further, the thickness of the dielectric layer 805 is not limited to 300 nm. It may be made thinner. It is preferable that the width of the near-field region generated by the metal structure is about 100 nm or more so that the dielectric layer can cover the area.

  In Embodiment 2, a method for manufacturing an RGB filter with a Bayer array and optical characteristics will be described. FIG. 10A shows a case where aluminum having a thickness of 20 nm is deposited as a metal thin film layer 1002 on the surface of a dielectric substrate 1001 made of a quartz substrate having a thickness of 525 μm, and a resist 1003 is applied thereon.

  Next, the resist 1003 is patterned using an EB drawing apparatus. The shape of the resist pattern is a pattern portion A1004 that is a portion obtained by patterning a shape in which squares having sides of about 130 nm are arranged in a square lattice pattern with a period of about 380 nm into about 10 μm square. Further, a shape in which squares with sides of about 110 nm are arranged in a square lattice pattern with a period of about 280 nm is referred to as a pattern portion B1005, and a shape in which squares with sides of about 80 nm are arranged in a square lattice pattern with a period of about 200 nm is referred to as a pattern portion C1006. . A structure in which each of these pattern portions is arranged as shown in FIG. 10B with a gap of 10 μm is produced. Using this resist pattern as an etching mask, metal thin film structure 1007 is fabricated by dry etching with plasma of a mixed gas of chlorine and oxygen.

  Next, a quartz thin film having a thickness of 500 nm is formed as a dielectric layer 1008 on the metal thin film structure 1007 by sputtering. The optical filter thus formed is shown in FIG.

  A light shielding layer may be formed in the region between the above-described pattern portions to prevent color mixing. In addition, if the thickness of the metal structure constituting each pattern portion is the same as in this embodiment, each pattern portion can be manufactured in the same process, and the boundary between the pattern portions is eliminated. Is also possible.

  As shown in FIG. 11, the pattern portions A, B, and C produced in this way have a transmission spectrum R indicated by reference numeral 1101, a transmission spectrum G indicated by reference numeral 1102, and a transmission spectrum indicated by reference numeral 1103. B. Each of these can function as a complementary color filter for RGB. Further, as in this embodiment, if the same thickness is produced for all the pattern portions, RGB complementary color filters can be produced in the same batch.

  The optical filter using the metal structure according to this embodiment can simultaneously produce optical filters having different absorption wavelengths and reflection wavelengths only by changing the size and arrangement period of the structures even when the film thickness is the same. .

  When an array of dye filters, which are general optical filters, is manufactured, it is necessary to coat different types of dyes using different processes. However, in the optical filter according to the present embodiment, it is possible to manufacture optical filters having different wavelengths by the same process, so that the manufacturing cost can be reduced.

  Further, the thickness of the dielectric layer 1008 is not limited to 500 nm. For example, in order to ensure an FSR of 100 nm or more in the blue wavelength region (wavelength 450 nm), the thickness of the dielectric layer is preferably about 690 nm or less when the refractive index is 1.46. On the other hand, it is also preferable that the width of the near-field region generated by the metal structure is about 100 nm or more so that the dielectric layer can cover the area.

  In Example 3, a manufacturing method and optical characteristics of the multilayer filter will be described.

  In FIG. 12A, aluminum is deposited as a first metal thin film layer 1202 with a thickness of 30 nm on the surface of a dielectric substrate 1201 made of a quartz substrate having a thickness of 1 mm, and an electron beam drawing (EB) is formed thereon. A resist 1203 is formed by coating.

  Next, the resist 1203 is patterned using an EB drawing apparatus. The resist pattern has a square shape with a side of about 120 nm and is arranged in a square lattice pattern with a period of about 400 nm. Using this resist pattern as an etching mask, the first metal thin film structure 1204 is fabricated by dry etching with plasma of a mixed gas of chlorine and oxygen.

  Next, a quartz thin film having a thickness of 300 nm is formed as a first dielectric layer 1205 on the first metal thin film structure 1204 by sputtering. The thickness of the first dielectric layer 1205 is not limited to 300 nm, but it is preferable to ensure an interlayer distance that does not cause near-field interaction with the second metal thin film structure layer to be produced in the next step. .

  Next, as shown in FIG. 12B, aluminum is deposited as a second metal thin film layer 1206 on the surface of the first dielectric layer 1205 to a thickness of 30 nm. Then, an electron beam drawing (EB) resist is applied as a resist layer on the second metal thin film layer 1206. Then, the resist layer is patterned by an EB drawing apparatus. The resist pattern has a square shape with a side of about 70 nm and is arranged in a square lattice pattern with a period of about 250 nm. Using this resist pattern as an etching mask, the second metal thin film structure 1207 is produced by dry etching with a plasma of a mixed gas of chlorine and oxygen.

  Next, as shown in FIG. 12C, a quartz thin film having a thickness of 400 nm is formed as a second dielectric layer 1208 on the second metal structure 1207 by sputtering.

  FIG. 13 shows a transmission spectrum of the laminated optical filter thus manufactured. The transmission spectrum 1301 of the first metal thin film structure of this filter has an absorption peak wavelength of about 650 nm, and the transmission spectrum 1302 of the second metal thin film structure has an absorption peak wavelength of about 450 nm. For this reason, the laminated filter transmission spectrum 1303 of the filter of this embodiment is in the form of these products. Therefore, it can be seen that the multilayer filter according to the present example functions as an optical filter that transmits green. That is, a filter that functions as a complementary color filter in each single layer can be made to function as a primary color filter by having a laminated structure.

  In the fourth embodiment, a filter having a transmission spectrum in which a plurality of transmission spectra are combined is obtained by alternately arranging metal structures having different sizes, that is, by arranging two metal structure groups in an overlapping manner. An example that can be realized with a single layer will be described.

  FIG. 15A shows an example in which a metal structure 1501 made of square aluminum having a side of 90 nm and a metal structure 1502 made of square aluminum having a side of 150 nm are arranged. The thickness of these metal structures is 60 nm, and the metal structures 1501 and 1502 are alternately arranged in a square lattice pattern with a period 1506. Here, the period 1506 is 250 nm.

  FIG. 15B shows a transmission spectrum 1503 of the optical filter thus manufactured. On the other hand, as a reference, a transmission spectrum 1504 of an optical filter in which square aluminum having a side of 90 nm is arranged in a square lattice with a thickness of 60 nm and a period of 250 nm is shown. Further, a transmission spectrum 1505 of an optical filter in which square aluminum having a side of 150 nm is arranged in a square lattice pattern with a thickness of 60 nm and a period of 400 nm is shown.

  As described above, since the optical filter according to the present example has the transmission spectrum 1503, it is possible to obtain a spectrum that expresses both characteristics of the two-layer filter although it has a single-layer structure.

  In addition, the transmission spectrum 1503 can be considered to have a filter characteristic having a maximum transmittance near the wavelength of 600 nm, and the function of two layers of complementary color filters can be expressed in one layer. In addition, the optical filter according to the present embodiment can be more easily manufactured as compared with the case where a single-layer metal structure filter is laminated.

  In this embodiment, an example in which the shape of two types of metal structures coexists in the plane has been given, but there may be three or more types of metal fine particles present in the plane, and the structure in which the period is modulated. The body group may be arranged so as to obtain a desired optical characteristic.

  This embodiment is an example in which an optical sensor using any one of the optical filters described in the first to fourth embodiments and an optical sensor are arranged in an array to constitute an imaging device, and this imaging device is incorporated in a digital camera. It is.

FIG. 23 is a schematic diagram of a photodetecting element using the optical filter of the present invention.
The light detection element 2507 introduces light incident from the outside through the microlens 2501 into the photoelectric conversion unit 2505. The photoelectric conversion unit generates charges according to incident light. In addition to the photoelectric conversion portion 2505, the light detection element includes an optical filter 2502, a dielectric layer 2503, an electric circuit portion 2504, and a semiconductor substrate 2506 disclosed in the present invention. The optical filter 2502 includes a structure capable of inducing plasmon resonance with respect to light, such as the metal structure 120 shown in FIG.

  FIG. 24 is a schematic diagram of an image sensor using the optical filter of the present invention.

  In FIG. 24, the pixel area 2600 has the above-described plurality of light detection elements (pixels) 2601a to 2603c arranged in a two-dimensional matrix of 3 rows × 3 columns. In FIG. 24, the pixel area 2600 is a two-dimensional matrix of 3 rows × 3 columns, but may be a matrix of 7680 × 4320 columns, for example.

  In FIG. 24, a vertical scanning circuit 2605 and a horizontal scanning circuit 2604 are circuits for selecting and reading out photodetection elements (pixels) arranged in the pixel area 2600.

  FIG. 25 shows a schematic diagram in which an image sensor configured as shown in FIG. 24 is incorporated in a digital camera.

  In FIG. 25, reference numeral 2701 denotes a camera body, 2709 denotes an eyepiece, 2711 denotes a shutter, and 2716 denotes a mirror.

  The image pickup device according to the present invention is 2706, and light enters the image pickup device 2706 through a photographing optical system (lens) 2702 disposed in the lens barrel 2705. Accordingly, charges are generated in each pixel of the image sensor 2706 according to the subject image, and the subject image can be reproduced corresponding to the generated charge. The subject image can be reproduced by the monitor display device 2707 and recorded on a recording medium 2708 such as a memory card.

  Since the optical filter according to the present invention is thinner than a color filter composed of a general pigment, the imaging device of the present invention shown here can be configured thinly. As a result, since the distance from the image sensor surface to the image sensor photoelectric conversion unit is shortened, the light use efficiency is improved. Thereby, the sensitivity of the image sensor according to the present invention can be improved.

Schematic diagram showing the first embodiment Transmission spectrum obtained by the first embodiment Schematic diagram showing the second embodiment Schematic diagram showing the fourth embodiment Schematic diagram showing the fifth embodiment Schematic diagram showing the fifth embodiment Schematic diagram showing the sixth embodiment Schematic diagram of the optical filter according to the first embodiment. Transmission spectrum obtained by the optical filter according to Example 1 Schematic diagram of an optical filter according to Example 2. Transmission spectrum obtained by the optical filter according to Example 2 Schematic diagram of an optical filter according to Example 3 Transmission spectrum obtained by the optical filter according to Example 3 Schematic diagram used when describing the embodiment of the present invention Schematic diagram and transmission spectrum of optical filter according to Example 4 Schematic diagram showing the third embodiment Diagram showing the relationship between the length of the metal structure and the resonance wavelength Schematic diagram defining the length of the metal structure Diagram showing the relationship between the length of the metal structure and the resonance wavelength Diagram showing the relationship between the thickness of the metal structure and the resonance wavelength Diagram showing the relationship between the period of metal structures and the resonance wavelength Diagram showing the relationship between wavelength and transmittance Schematic diagram of photodetection element Schematic diagram of image sensor Schematic diagram of digital camera

Explanation of symbols

DESCRIPTION OF SYMBOLS 110 Dielectric board | substrate 120 Metal structure 121 1st metal structure 122 1st metal structure 130 Dielectric layer 140 1st direction 141 1st length 145 period 150 2nd direction 151 2nd length 155 period 160 thickness of metal structure 170 thickness obtained by subtracting thickness of metal structure from thickness of dielectric layer 201 transmission spectrum R
202 Transmission spectrum G
203 Transmission spectrum B
301 region 302 region 303 region 401 first metal structure 402 first metal structure group 403 first metal structure 404 first metal structure group 405 period 406 period 407 first metal structure 408 second Metal structure 501 First metal structure group 502 First direction 503 Second direction 504 First length 505 Second length 506 Second metal structure group 507 Third length 508 First 4 length 701 dielectric substrate 702 first metal structure group 703 first dielectric layer 704 third metal structure group 705 second dielectric layer (other dielectric layers)
801 Dielectric substrate 802 Metal thin film layer 803 Resist 804 Metal thin film structure 805 Dielectric layer 901 Transmission spectrum R
902 Transmission spectrum G
903 Transmission spectrum B
904 Reflection spectrum R
905 reflection spectrum G
906 Reflection spectrum B
1001 Dielectric substrate 1002 Metal thin film layer 1003 Electron beam drawing resist 1004 Pattern part A
1005 Pattern part B
1006 Pattern part C
1007 Metal thin film structure 1008 Dielectric layer 1101 Transmission spectrum R
1102 Transmission spectrum G
1103 Transmission spectrum B
1201 Dielectric substrate 1202 First metal thin film layer 1203 Resist 1204 First metal thin film structure 1205 First dielectric layer 1206 Second metal thin film layer 1207 Second metal thin film layer 1208 Second dielectric layer 1301 Transmission spectrum 1302 Transmission spectrum 1303 Multilayer filter transmission spectrum 1401 Dielectric substrate 1402 Metal 1403 Metal upper surface 1404 Metal lower surface 1501 Metal structure 1502 Metal structure 1503 Transmission spectrum 1504 Transmission spectrum 1505 Transmission spectrum 1506 Period 1601 First metal structure 1602 First 1 metal structure group 1603 second metal structure 1604 second metal structure group 1801 first length 1802 second length 2201 transmission spectrum 2202 transmission spectrum

Claims (16)

An optical filter that transmits or reflects light of a first wavelength,
A dielectric substrate;
A first metal structure group in which a plurality of first metal structures are two-dimensionally provided on the surface of the dielectric substrate in a state of being isolated in an in-plane direction;
A dielectric layer covering the first metal structure group,
The first metal structure has a first length in a first direction and a second length in a second direction orthogonal to the first direction. The length and the second length are less than or equal to the first wavelength,
The first metal structure and the light incident on the dielectric substrate or the dielectric layer resonate with each other, and the first plasmon is induced by the localized plasmon induced on the surface of the first metal structure. While setting the wavelength transmittance to the minimum value or the reflectance to the maximum value ,
The first length and the second length are in the range of 110 nm to 160 nm, and the thickness of the first metal structure is in the range of 10 nm to 100 nm, and the first metal structure An optical filter , wherein a period in which a body is provided is in a range of 340 nm to 450 nm, and the first wavelength is in a range of 550 nm to less than 650 nm . An optical filter that transmits or reflects light of a first wavelength,
A dielectric substrate;
A first metal structure group in which a plurality of first metal structures are two-dimensionally provided on the surface of the dielectric substrate in a state of being isolated in an in-plane direction;
A dielectric layer covering the first metal structure group,
The first metal structure has a first length in a first direction and a second length in a second direction orthogonal to the first direction. The length and the second length are less than or equal to the first wavelength,
The first metal structure and the light incident on the dielectric substrate or the dielectric layer resonate with each other, and the first plasmon is induced by the localized plasmon induced on the surface of the first metal structure. While setting the wavelength transmittance to the minimum value or the reflectance to the maximum value,
The first length and the second length are in the range of 90 nm to less than 130 nm, and the thickness of the first metal structure is in the range of 10 nm to 100 nm, and the first metal structure An optical filter , wherein a period in which a body is provided is in a range of 260 nm to 340 nm, and the first wavelength is in a range of 450 nm to less than 550 nm . An optical filter that transmits or reflects light of a first wavelength,
A dielectric substrate;
A first metal structure group in which a plurality of first metal structures are two-dimensionally provided on the surface of the dielectric substrate in a state of being isolated in an in-plane direction;
A dielectric layer covering the first metal structure group,
The first metal structure has a first length in a first direction and a second length in a second direction orthogonal to the first direction. The length and the second length are less than or equal to the first wavelength,
The first metal structure and the light incident on the dielectric substrate or the dielectric layer resonate with each other, and the first plasmon is induced by the localized plasmon induced on the surface of the first metal structure. While setting the wavelength transmittance to the minimum value or the reflectance to the maximum value,
The first length and the second length are in the range of 60 nm to less than 100 nm, and the thickness of the first metal structure is in the range of 10 nm to 100 nm, and the first metal structure An optical filter , wherein a period in which a body is provided is in a range of 180 nm to 280 nm, and the first wavelength is in a range of 350 nm to less than 450 nm . The optical filter according to claim 1, wherein the first length and the second length are the same . The optical filter according to claim 4 , wherein the first metal structure has a square shape . The optical filter according to any one of claims 1 to 5, wherein the first metal structure is a mixture or alloy containing aluminum or aluminum. Wherein a dielectric constant dielectric substrate has optical filter according to any one of claims 1 to 6 and the dielectric constant of the dielectric layer has is characterized in that it is the same. Wherein the dielectric substrate, the dielectric layer is silicon dioxide, the optical filter according to any one of claims 1 to 7, characterized by being composed of titanium dioxide, by one of the silicon nitride. An optical filter that transmits or reflects light of a first wavelength,
A dielectric substrate;
A first metal structure group in which a plurality of first metal structures are two-dimensionally provided on the surface of the dielectric substrate in a state of being isolated in an in-plane direction;
A dielectric layer covering the first metal structure group,
The first metal structure has a first length in a first direction and a second length in a second direction orthogonal to the first direction. The length and the second length are less than or equal to the first wavelength,
The first metal structure and the light incident on the dielectric substrate or the dielectric layer resonate with each other, and the first plasmon is induced by the localized plasmon induced on the surface of the first metal structure. While setting the wavelength transmittance to the minimum value or the reflectance to the maximum value,
Separately from the first metal structure group, there is a second metal structure group in which a plurality of second metal structures are two-dimensionally provided in an in-plane direction of the dielectric substrate. And
The second metal structure has a third length in the first direction and a fourth length in the second direction, and the third length and the fourth length The length is equal to or less than a second wavelength different from the first wavelength;
The third length is different from the first length, or the fourth length is different from the second length;
The first metal structure group and the second metal structure group are arranged in different regions on the surface of the dielectric substrate,
The second metal structure and the second plasmon induced on the surface of the second metal structure by resonance between light incident on the dielectric substrate or the dielectric layer, An optical filter characterized in that the transmittance of wavelength is a minimum value or the reflectance is a maximum value . An optical filter that transmits or reflects light of a first wavelength,
A dielectric substrate;
A first metal structure group in which a plurality of first metal structures are two-dimensionally provided on the surface of the dielectric substrate in a state of being isolated in an in-plane direction;
A dielectric layer covering the first metal structure group,
The first metal structure has a first length in a first direction and a second length in a second direction orthogonal to the first direction. The length and the second length are less than or equal to the first wavelength,
The first metal structure and the light incident on the dielectric substrate or the dielectric layer resonate with each other, and the first plasmon is induced by the localized plasmon induced on the surface of the first metal structure. While setting the wavelength transmittance to the minimum value or the reflectance to the maximum value,
Having two or more of the first metal structures in the in-plane direction of the dielectric substrate;
The optical filter, wherein the two or more first metal structure groups are arranged in an overlapping region . An optical filter that transmits or reflects light of a first wavelength,
A dielectric substrate;
A first metal structure group in which a plurality of first metal structures are two-dimensionally provided on the surface of the dielectric substrate in a state of being isolated in an in-plane direction;
A dielectric layer covering the first metal structure group,
The first metal structure has a first length in a first direction and a second length in a second direction orthogonal to the first direction. The length and the second length are less than or equal to the first wavelength,
The first metal structure and the light incident on the dielectric substrate or the dielectric layer resonate with each other, and the first plasmon is induced by the localized plasmon induced on the surface of the first metal structure. While setting the wavelength transmittance to the minimum value or the reflectance to the maximum value,
Having two or more of the first metal structures in the in-plane direction of the dielectric substrate;
The periods in which the first structures constituting the two or more first metal structure groups are provided are different from each other,
The optical filter, wherein the two or more first metal structure groups are arranged in an overlapping region . An optical filter that transmits or reflects light of a first wavelength,
A dielectric substrate;
A first metal structure group in which a plurality of first metal structures are two-dimensionally provided on the surface of the dielectric substrate in a state of being isolated in an in-plane direction;
A dielectric layer covering the first metal structure group,
The first metal structure has a first length in a first direction and a second length in a second direction orthogonal to the first direction. The length and the second length are less than or equal to the first wavelength,
The first metal structure and the light incident on the dielectric substrate or the dielectric layer resonate with each other, and the first plasmon is induced by the localized plasmon induced on the surface of the first metal structure. While setting the wavelength transmittance to the minimum value or the reflectance to the maximum value,
Separately from the first metal structure group, there is a second metal structure group in which a plurality of second metal structures are two-dimensionally provided in an in-plane direction of the dielectric substrate. And
The second metal structure has a third length in the first direction and a fourth length in the second direction, and the third length and the fourth length The length is equal to or less than a second wavelength different from the first wavelength;
The third length is different from the first length, or the fourth length is different from the second length;
The first metal structure group and the second metal structure group are arranged in an overlapping region,
The second metal structure and the second plasmon induced on the surface of the second metal structure by resonance between light incident on the dielectric substrate or the dielectric layer, An optical filter characterized in that the transmittance of wavelength is a minimum value or the reflectance is a maximum value . An optical filter in which an optical filter that transmits or reflects light of a first wavelength and an optical filter that transmits or reflects light of a second wavelength are stacked,
A dielectric substrate;
A first metal structure group in which a plurality of first metal structures are two-dimensionally provided on the surface of the dielectric substrate in a state of being isolated in an in-plane direction;
A dielectric layer covering the first metal structure group,
The first metal structure has a first length in a first direction and a second length in a second direction orthogonal to the first direction. The length and the second length are not more than the first wavelength, and
Another dielectric layer is formed on the surface of the dielectric layer,
A plurality of second metal structures two-dimensionally provided between the surface of the dielectric layer and the other dielectric layer so as to be isolated in the in-plane direction of the surface of the dielectric layer; A metal structure group of
A second metal structure constituting the second metal structure group has a third length in the first direction and a fourth length in the second direction; The third length and the fourth length are not more than a second wavelength different from the first wavelength, and
The first length is different from the third length, or the second length is different from the fourth length, or the period in which the second metal structure is provided and the first length Unlike the period in which the metal structure is provided,
The local plasmon induced on the surface of the first metal structure causes the transmittance of the first wavelength to be a minimum value or the reflectance to be a maximum value; and
A laminated optical filter characterized in that the transmittance of the second wavelength is minimized or the reflectance is maximized by localized plasmons induced on the surface of the second metal structure . A light receiving element comprising the optical filter according to claim 1 . The light receiving element according to claim 14, further comprising a CCD sensor . 15. The light receiving element according to claim 14, further comprising a CMOS sensor .

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